us contingent; indeed their independence of each other is just the conception of contingency. Since, however, each of them was the necessary effect of its causes, the chain of which has no beginning, it is evident that contingency is merely a subjective phenomenon, arising from the limitation of the horizon of our understanding, and just as subjective as the optical horizon at which the heavens touch the earth.
Since necessity is the same thing as following from given grounds, it must appear in a special way in the case of every form of the principle of sufficient reason, and also have its opposite in the possibility and impossibility which always arises only through the application of the abstract reflection of the reason to the object. Therefore the four kinds of necessity mentioned above stand opposed to as many kinds of impossibility, physical, logical, mathematical, and practical. It may further be remarked that if one remains entirely within the province of abstract concepts, possibility is always connected with the more general, and necessity with the more limited concept; for example, "An animal may be a bird, a fish, an amphibious creature, &c." "A nightingale must be a bird, a bird must be an animal, an animal must be an organism, an organism must be a body." This is because logical necessity, the expression of which is the syllogism, proceeds from the general to the particular, and never conversely. In the concrete world of nature (ideas of the first class), on the contrary, everything is really necessary through the law of causality; only added reflection can conceive it as also contingent, comparing it with that which is not its cause, and also as merely and purely actual, by disregarding all causal connection. Only in this class of ideas does the conception of the actual properly occur, as is also shown by the derivation of the word from the conception of causality. In the third class of ideas, that of pure mathematical perception or intuition, if we confine ourselves strictly to it, there is only necessity. Possibility occurs here also only
